As eco-friendly vehicles, electric vehicles or hybrid cars are increasing. Such vehicle includes, mounted thereon, a power supply device constituted by a battery assembly in which a plurality of batteries are coupled to one another.
As those kinds of power supply devices, there is one which has a printed circuit board constituted by a hard board on which signal output lines for outputting voltages of batteries to the outside are wired by being connected to the batteries in order to detect the voltages of the respective batteries. The printed board and bus bars for wiring fixed to terminals of the respective batteries are coupled to each other with coupling terminals (see, for example, Patent Document 1).